Equity Affiliates (Table of Summarized Financial Information of Equity Affiliates) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Schedule of Equity Method Investments [Line Items]
Total Current Assets	$ 5,825.8	$ 6,363.0
Total Noncurrent Assets	35,233.7	33,211.6
Total Current Liabilities	4,218.6	4,179.6
Total Noncurrent Liabilities	19,491.1	16,721.3
Sales and other income	12,037.3	12,100.6	$ 12,600.0
Operating income	(877.0)	4,466.1	2,494.6
Net income	(354.4)	3,862.4	2,338.6
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Total Current Assets	3,968.5	3,197.2
Total Noncurrent Assets	16,490.1	14,719.8
Total Current Liabilities	1,441.4	1,138.3
Total Noncurrent Liabilities	12,626.3	11,690.4
Sales and other income	5,831.7	5,666.4	5,192.9
Financing revenue	1,137.3	1,128.6	1,011.3
Gross profit	2,849.0	2,722.0	2,465.5
Operating income	2,206.6	2,149.3	1,847.4
Net income	$ 1,263.6	$ 1,209.5	$ 1,062.9